title: Nonthyroidal illness: a risk factor for coronary calcification and arterial stiffness in patients undergoing peritoneal dialysis?
abstract: OBJECTIVE
  Low triiodothyronine levels, as part of the nonthyroidal illness syndrome, are common in dialysis patients and have repeatedly been shown to be associated with increased (cardiovascular) mortality rates. We hypothesized that increased vascular calcification may mediate this relationship.
  
  
  METHODS
  A total of 84 patients from the Stockholm region receiving maintenance peritoneal dialysis were included in the study. Serum concentrations of free triiodothyronine (fT3), thyroxine and thyroid-stimulating hormone were measured. Coronary artery calcium (CAC) scores were assessed by cardiac computed tomography scans. Surrogates of arterial stiffness included aortic diastolic and systolic blood pressures, pulse pressure, augmentation pressure and Buckberg's subendocardial viability ratio measured by pulse waveform analyses. Patients were subsequently followed, and events of death and censoring were recorded. Thyroid hormone concentrations were associated with CAC scores, measures of arterial stiffness and all-cause mortality. The associations between CAC scores and arterial stiffness surrogates and mortality were also determined to evaluate a possible causal pathway.
  
  
  RESULTS
  Both CAC scores and arterial stiffness surrogates were substantially higher in individuals with low fT3 levels. These associations persisted in multivariate logistic and linear regression analyses. During a median (interquartile range) follow-up of 32 (22-42) months, 24 patients died. Both fT3 levels below the median value [HR crude 4.1, 95% confidence interval (CI) 1.4-12.6] and CAC scores above the median value (HR crude 5.8, 95% CI 1.7-20.1) were strongly associated with mortality.
  
  
  CONCLUSIONS
  In patients undergoing peritoneal dialysis, fT3 levels were strongly associated with arterial stiffness, coronary artery calcification and mortality. We speculate that the association between nonthyroidal illness and mortality may be partly mediated by acceleration of vascular calcification.
authors.affiliation: Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden, The Netherlands; Baxter Novum, CLINTEC, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Christiaan L
authors.initials: CL
authors.lastname: Meuwese
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Carrero
authors.forename: Iván
authors.initials: I
authors.lastname: Cabezas-Rodríguez
authors.forename: Olof
authors.initials: O
authors.lastname: Heimburger
authors.forename: Peter
authors.initials: P
authors.lastname: Barany
authors.forename: Bengt
authors.initials: B
authors.lastname: Lindholm
authors.forename: Abdul R
authors.initials: AR
authors.lastname: Qureshi
authors.forename: Jonaz
authors.initials: J
authors.lastname: Ripsweden
authors.forename: Friedo W
authors.initials: FW
authors.lastname: Dekker
authors.forename: Peter
authors.initials: P
authors.lastname: Stenvinkel
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D005067:Euthyroid Sick Syndromes / Q000150:complications* / Q000175:diagnosis / Q000401:mortality; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications* / Q000401:mortality / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis; D012307:Risk Factors; D015996:Survival Rate; D061205:Vascular Calcification / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D059289:Vascular Stiffness
keywords: arterial stiffness; coronary artery calcium score; peritoneal dialysis; thyroid hormones; vascular calcification